A typical ultrasonic transducer always has a steep resonance curve with a very high Quality factor, and high mechanical amplitude and high motor efficiency will be available only if the ultrasonic transducer operates at its resonant frequency. Thus the ultrasonic transducer shall be driven with its resonant frequency signal by a drive circuit thereof.
An operating frequency of a resonating device swings back and forth in certain range, and since the frequency varies in the range predetermined by a line, the operating frequency may deviate from a real resonance point for the majority of an operating period of time, so that the device operating at a frequency other than the resonance point may tend to come with a waste of power and degraded efficiency.
In order to obtain the resonant frequency of the ultrasonic transducer, an ultrasonic energy drive system needs, for example, an ultrasonic generator, to search for the resonant frequency of the transducer and then drives the transducer with that frequency so that the transducer operates in a resonant state.
One existing way to search for the resonant frequency of the transducer currently is frequency sweep, that is, a search for the resonant frequency is made by increasing or decreasing the frequency of an energy resource progressively, but the search may be made slowly and inefficiently. For example, if the frequency sweep is performed from 50 KHz to 60 KHz, then a period of time with 10,000 determinations may be required in order to guarantee accuracy of a search result, which is inefficient.